Machine switching telephone system.



F. R. MCBERTYJ MACHINE SWITCHING TELEPHONE SYSTEM. APPLICATION FILEDMAR.2. 1914. RENEWED IULY 30. 915- Pavtented Oct. 26, 1915.

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AMY.

F. R. McBERTY V MACHINE SWITCHING TELEPHONE SYSTEM APPLI'CATION FILEDMAR.2. i914- RENEWED JULY 30.1915.

1,1571381. Patented 0ct.26,1915

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F. R.. McBERTY.

MACHINE swncHma TELEPHONE SYSTEM. APPLICATION FILED MAR. 2-1914- RENEWEDJULY 30. IBIS.

Patented Oct. 26, 1915.

9 SHEEIS-SHEET 4.

W/fnesses:

' by I MAff' F. R. MCBERTY.

MACHINE SWITCHING TELEPHONE SYSTEM. APPLICATION FILED MAR.2. I914.RENEWED JULY 30.1915.

151573881. Patented w. 26, 1915 9 SHEEIS-SHEET 5,

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F. R. McBERTY. MACHINE SWITCHING TELEPHONE SYSTEM. APPLICATION FILEDMAILZ. I914- RENEWED JULY 3011915. 1,157, 31, Patented (M26, 1915.

9 SHEETS-SHEET 6.

F. R. MCBERTY. MACHINE SWITCHING TELEPHONE SYSTEM. APPLICATION HLEDMAR.2. 1914. RENEWED JULY 30. I915- 1 157 31 Patented Oct. 26, 1915.-

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Pateutd Oct. 20, 1915.

F. R. McBERTY.

MACHINE SWITCHING TELEPHONE SYSTEM.

APPLICATION FILED MAR. 2. 19M RENEWED JULY 30,19l5.

W/fnesses:

. Fran/r /'I. M

v F. R- MCBERTY. MACHINE SWITCHING TELEPHONE SYSTEM. APPLICATION HLEDmm. 2. I914. nsmzwzn my 30. ms,

1,157,881. Patamad; Get 2%, 1915;,

9 sakes-swam UNITED sTA'rEs PAT NT "OFFICE.

FRANK ROBERT MCBERTY, OF ANTWEBP, BELGIUM, ASSIGNOR TO WESTERN ELECTRICCOMPANY, OF NEW YORK, N. Y., A CORPORATION OF ILLINOIS.

- MACHINE SWITCHING TELEPl -IONE SYSTEM.

Specification of Letters Patent.

Patented Oct. 26, 191 5.

Application filed March 2, 1914, Serial No. 821,875.. Renewed July 30,1915. Serial No. 42,830.

To all whom it may concern Be it known that l, FRANK ltinnsirrll/IUBERTY, a citizen of the United States, residing at 49 BoulevardLeopold, Antwerp, Belgium, have invented certain new and usefullmproven'ients in Machine Switching Telephone Systems, of which thefollowing is a full, clear, concise, and exact description.

This invention relates to improven'ients in machine telephone switchingsystems, and has to do more particularly with systems in which theextension of the desired connection from a calling line to a called lineis ac complished by automatic switching apparatus directly or indirectlyunder the control of a subscriber at. the calling substation. Many ofthe features to be described, ho'w 'ever, are 'not restricted to systemsof this In British Patents Nos. 26,079/10 and 21,259/11' there aredescribed automatic telephone switching systems in which impulsestransmitted from a calling station and representing the number of thewanted line are received at the central oflice by registering deviceswhich thereupon act as controllers to govern the selectingoperationsnecessary to extend the connection to the line represented bysuch registration. Furthermore, in British Patent No. 21,259/11 there isdescribed a system and arrangement in which translation takes place insuch registering and controlling devices whereby, although thecontrolling mechanism located at the substation may be constructed andoperated according to one system of notation. the actual selection ofthe desired line and of the v l trunk l nes over which it may be reachedmay take place in accordance with some other system of notation,

One of the principal features of this invention relates to systems ofthe character described. in the patents referred to and relates moreparticularly to an improved and novel registering and controllingequipment and means for associating the same with the calling substationand the selectors to be controlled. Most specifically this feature.

of the invention involves the use of powerdriven registering andcontrolling devices in such registering and controlling equipment and ofimproved and novel circuitsand arrangen'ients whereby such devices maybe controlled and operated accurately and at high speed to positivelyand precisely control the operation of the automatic switching devicesto be selectively and accurately set in response to the controllingoperation at the called subscribers substation.

Other novel features of the invention, such particularly as relate tooperations of various sequence switches (steeringswitches) used thereinand the inter-operation of such switches will.more fully appear from thedetailed description of the invention.

In the drawings, Figure 1 shows the circuits and apparatus of asubscribers line and Fig. 1 the first line tinder adapted to extend theconnection of such. line when calling; Figs. 2 and 2 illustratediagrammatically the second line finder and the connecting circuitassociatr-id therewith, together with the-group selector and otherapparatus associated with such connecting circuit: Figs. 3 and 3illustrate the circuits and apparatus of a final selector; Figs. l and4. illustrate the circuits and appara tus of a registering andcontrolling equip ment adapted to be associated with the connectingcircuit shownlfi Figs. 2 and 2, to control the group selector and finalselector shown. Fig. 5 is a detail of the structure of the finalselector showing wherein the final selectors used in the systemdisclosed dili'cr from the final selectors disclosed in theBritishlatent No. 21.259/11 above referred to. l igs..1,-'1, 2, 2. 3, 3.-l and. t taken together illustrate diagrammatically a system involvingthe invention. Fig. 1 should be placed to the right of Fig. 1, Fig. 2 tothe right of Fig. 1. Fig. 2 to the right of Fig. 2, Fig. 3 to the rightof Fig. 2. Fig. 3 to the right of Fig. 3-. Fla. 4 below Fig. 2, and Fig.4* below Fig. 2".

The line finders. group selectors and sequence switches are of typesalready known made that in Fig. 2 the sequence switch confacts of thethree sequence switches shown thereon are associated with, the sequenceswitch indicated in that portion of the figure separated from the rcniaining portions by dotted lines. The nnal se ector switch differs fromthe final selector switches of this type previously known only by the.

addition of two extra notches in the interrupter plate 01 the topthereoi, between the first 10 notches thereof and the second tacts' ofthese lines are. arranged in ten levels of twenty lines each. Betweenthe bank of the one hundred lines individual toone hundred, and the bankof lines individual to another hundred, that is to say, between thefirst tenlines of each level and the second ten lines of each levelthere is 'a' spacing plate. In selector switches of this type previouslyknown the spacing between the two banks of line contacts was Without.efi'ect. as the interiupter plate at the top oi the selector-.Was uncutover the portion there: of corresponding to the spacing plate. in thefinal selector switches as used herein,

' however, there are two notches cut in the lines passed over plustwo.

portion. of the interrupter piate correspond-- .ing to the spacing platefor purposes herein described. That is to say, in. selecting a hue inthe first set'bf ten lines on. a given. level. the interrupter willoperate a number of times corresponding to the number of lines passedover, whereas, in selecting a line in the second set of ten contacts onsuch gi'vei'i level, the interrupter will operate a number of timescorresponding to the number of This will be readily understood from anexamination of Fig. 5 in which the notches 0; represent the notches ofsuch interrupter plate corresponding to the first set of ten lines onthe given level of the selector; the "notches 6 representthe notches insuch plate corresponding" to the second set of ten lines on sequenceswitches 100arein first or normal position. Such idle line finders will,there- :t'ore, start in motion, moving their brushes 125, 126, 127, 128over the terminals 129, 130, 131, 132 of thedines appearing in such linefinders, and testing such lines in the usual way. As one of them,however, brings its brushes'into contact With. the terminals of thecalling line, it will find upon the terminal 132 of such line aselectable potential produced by the energization of the line relay 121and determined by the resistances 133'and 134. Immediately thatthe'brl'lsh 128 comes in contact with the terminal 132 upon which suchselectable potential exists,

the first. line finders of this group which'are at this time in idlecondition; that is, whose the test relay 135 will be energized over thesprings 102 bottom, 108 top and either the spring 106' or theinterrupter brush 136.

The cnergization of this relay 1,35 closes through. its armature a lowresistance holding winding for itself, the closure of such circuitthrough such Winding so reducing the potential upon the terminal 132that such potential is no longer selectable, and any other line finderwhose brush 128 comes in contact with such terminal 132 will not bestopped. The carriage of the line finder "which has thus seized theline, continues in motion,'however, until its brushes are properlycentered upon the terminals of the calling line, at Whichtime thecircuit such level, and the two notches (I represent the two extra oradditional notches which have been added as above indicated for purposeshereinafter described.

The invention as disclosed herein will be best understoodfrom adescription or the ,operati m of thesystem shown.

Assuming that the sul'xscriber at the substation indicated at 120desires conmiction with the subscriber indicated at 320, whose Iuunberis 307. he first removes his receiver from. its switch hook, therebyclosing a circuit for the line relay 121 which, on its ener- ,Q'izaticn,closes a circuit tor and energizes the pilot 'relay'122 common to agroup of incoming lines which appear multiplied upon a given group oifirst line finders such as the one shown in Fig. 1. Relay 122 closes aclrcuit over the sequence switch springs through the interrupter brush136 will be open, and the shunt being removed from around the powercontrol test relay 137, such relay will be energized, opening thecircuit of the power magnet 123 and closing the circuit of the holdingmagnet 138 over the springs 105 top and 107, thereby positively stoppingthe brush carriage in proper posi- 5 tion. The energization of the relay137 has also driven the sequence switch 100 out of its first into itssecond position. In this n'lovcment of the sequence switch a test guardis maintained upon the terminal 132 and the seized line through thespring 11.2 bottom, the spring 102 bottom being opened as the sequenceswitch leaves its first position. In the second position the springbeing closed, the ut-ofi' relay 139 of the calling line is energized,causing the dei ncrgization of the line relay 121 and the consequentdeenergization of the pilot relay 122, provided no other lineot' thisgroup is at this time calling and not as yet been seized by a linefinder. The deenergization of the relay 121 opens the battery circuit tothe terminals 132, and the line now having been seized and beingmaintained busy, no selectable potential is possible upon its testterminal 132. The sequence switch 1009011 coming into its secondposition, has established a circuit 1.01 and'103 tor the power magnet123 of all spring 02 bottom, back contact of relay 237 11d spring" 03top tor the, pow magnets 320 of the idlc second line linden in which thecircuit. connected to the first line finder snown. appears in multiple.The brush carriages of such idle line finders, thcrcfoir, move thebrushes 2 8, 22-0, 2 -30 over the contacts 231, 23 3.34 of the variousline s p-caring: in such line finders. The. scqurncc switch 100, oncoming, into its second position, by closing ihcsprings 108 bottom. 106top and 107, has placed selectable. potential on the. terminal 22-3 ofthe trunk lino or circuit connected to the first line iimlcr associatedwith such sequence switch 3.00. ii "hen the. brush 230 of one of suchsecond lino finders comes in contact with the terminal 554-, upon whichthis selectable potential e ists, the test relay 2.35 will be energized,the circuit for such relay including the springs 30- top, 05 top andeither the interrupter brush 250 or the spring 606 top. Such relay will,there fore, be energized, closing in parallel to its right-hand windingthe low resistance holdinf: winding, which will so reduce the poten tialupon the terminal 234 that no other sec-- oiul line tinder can now seizetho line to which such terminal is individual. The brushes of thescizint second line finder, llliWGVQl'. will continue to more until whenthey arc centered upon the terminals of the seized 1w. the circuit overthe interrupter brush is opened, and. the shunt being there by removedfrom around the power-control test rclay 223. such relay is energised tostop the switch in the usual manner by opening tho circuit of the powermagnet 224' and closing the circuit of the holding n'iagnct 235 at thesame time driving the sequence switch 000 out of its first into itssecond I sition by closing: a circuit over tho spring (it)? top. As the.sequence, switch .300 learns its first position, and until. it haspassed through its seventh position, a busy test guard. is maintainedupon the terminal 33% by the closurc of the spring 010, connectingground to such terminal.

As the sequence switch 600 was passii'ig from its first into its secondposition, the. spring (311 was closed suliiciently long to drive thesequcnce switch 200 out of its first position, the circuit for movingsuch sequence switch including the spring 202 bot tom. This sequenceswit ,-.h comes to rest in its sccond position. in position 2 of thesequence. switch 600. and in position 2 of the sequence switch 200, theselection of an idle registering and controlling mechanism will takeplace. Bcforc considering this operation, however. the various effectsof the seizure of the circuit connected to the first line, finder; andthe nimement of the sequence switch 200 into position 2 will beconsidered. When the test rcla y 235 was 6H6!- giz'cd, the circuittherefor also included the relay 1.37, to maintain it energized, and relay 13? being energized the sequence switch 100 is-Inovcd from itssecond position to its fifth position. in position 5 the circuit forrelay 137 will include the resistance 140 as well as the resistance 141,but suchrel'ay will be maintained energized so long as the spring 610top is closed. In position 5 of the sequence switch .100, the spring 110being open, the circuit for the cut-off relay 139 now includes thespring 102, the relay 135 and the spring 207, the sequence switch. 200now beingiin' the second position. in this position also the spring 112,is open-and the circuit of the calling line. is extended over thesprings 210 top and 211 top to the repeating coi'l 239. 600 came intoits second position, the springs 604 bottom, 639 top, 605 bottom,iilliibOttOIH and 013 bottom were closed. If at this time the sequenceswitch 700 individual to the connecting circuit shown is in suchposition that an idle registering and controlling equipment connected.by it to the leads shown, the. relay 1240 will be, energized over acircuit .cl'uding springs 703, 619 bottom, 704c'rclay i ii and spring405 of the sequence switch 400 ing' and -ntrolling equipment. ever, aepinent with which the leads are connected over such sequence switch.700 is already .a ..y, the test circuit including the relay of someother connecting circuit will already be energized over the circuitincluding the relay 4% and insutlicicnt cur- "ol through the relay 2&0shown, to energize it. A circuit will, therefore, be established overthe baclc contact of such relay E240, spring (312-5 bottom and spring702 to cause the sequence switch 700 to move and it will continue inmotion until on closing the circuit from the leads of the conwillihcopened and the relay 237 being energized in parallel with the relay 220the sequence switch 600 will be driven through sequence switch springs602 top and (507 top from its second into its ,third position. In thisposition the relay 240 and the relay 237 are directly connected over thespring (519 bottom and over the spring 704- hottoni, for example asshown, to the starting relay 426. This idle registering and controllingequipment is now seized and is inaccessible to any other connectingcircuit having access thereto until it has performed its function or hasbeen released by the hanging ,up of the receiver of the callingsubscriber, as will be hereinafter described. As the sequence 1 switch600 moved into its third position it closed the circuit over the spring609 to drive the sequence switch 200 also to its third posltion. In thisposition springs 210 As the sequence switch bottom and 211 bottom areclosed, and the impulse receiving circuit from the subscriberssubstation to the registering and controlling equipment is now complete,such circuit being traceable from battery througl'i brush 126 and"terminal 130 of the first line finder switch over the subscribers lineand through his substation, terminal 129 and brush 125 of the first linefinder switch, terminal'231 and brush'227 of the second line finderswitch, spring 211 bottom to ground and back to battery. This circuitbeing established, and the relay 426 being energized, as beforedescribed the sequence switch 400 is driven out of its first and intoits fourth position. It will be observed that the calling .subscriberssupervisory relay 241, which at this time controls rest-oration andwhich in position 2 and position 4 and positions subsequent thereto isdirectly uuder the control of the calling subscriber, is energized bythe closure of a spring 205. The apparatus will now await the sending ofimpulses by the calling subscriber, such .im'pulses being arranged ingroups corresponding to the complement of the digits of the numericaldesignation of the called. subscribers station that is to say, thecalled subscribers numher being assumed to be 307, thecalling subscriberwill transmit to the central station three series of impulses, the firstseries comprising seven impulses, the second series comprising tenimpulses, and the third series comprising three impulses. In each ofthese series of impulses the last impulse sent will be relatively longerthan the other impulses of the series, which other impulses are, infact, quite short. The sender by which these impulses are sent may be,oi any desired structural character, provided that the impulses are sentin a complementary manner, and that the last of each oi. the groups ofimpulses sent by such device is relatively longer than the otherimpulses of such group. A sender is diagrammatically shown capable ofaccomplishing the necessary fund tions, and in which the setting of thesender produces no impulse in the circuit. The

' impulses as produced in the system as disclosed are interruptions ofthe circuit.

The system herein disclosed is for clearness shown only as a 1000 linesystem. In such a system there willbe five groups of final selectors,each accessible to 200 lines thereof, and the group selectors used willhave only five of the ten banks thereof utilized, one bank of contactsbeing connected tot-he trunk lines of the group of final selectorsindividual to one group of 200 lines, another connected to anothergroupof final selectors individual to another 200 lines, and so on. In accordance with the translating system disclosed herein, the selection in thegroup selector of the trunk line leading to the group of lines havingthe proper hundreds digit is such that if the 100s digit of the desiredline is zero or one, the tripping spindle of the group selector will beadjusted to release the proper set of brushes on the brush carriage bythe movement of such spindle one step or stage. If the 100s digit of thedesired line is two or three, such spindle will be moved three stepsorstages. If the 100s digit is.four or five, the spindle will bemovedlfive steps or stages. If the 100s digit is six or seven, suchspindle will be moved seven steps or stages, and finally if the 100sdigit is eight or nine, such spindle will be moved. nine steps orstages. Of course, it will be understood that if the sys 'tem is formore than 1000 lines that the intermediate steps or stages, that is,second, fourth, sixth, eighth and tenth will be reserved for' use when atrunk line is desired leading to the groups of selectors having accessto the lines of such second thousand. In a. 1000 line system as hereindisclosed, the trunk lines may be, and it will be assumed, are,connected to the alternate levels of contacts in such group selector. Itwill be further understood that by properly rearranging the trippingteeth. upon the trippingspindle, the live levels and terminals which areusedmay be. arranged, if desired, adj-accntly to each other, so that thefirst level will. be selected by a single step of the tripping spindle,the second level by three steps oi such. spindle,the third level by fivesteps of such spindle, and so 011.. Furthermore, if

by one step of the tripping spindle of the 1 group selector, a linewhose 100s' digit is 1 by two steps of the tripping spindle, and so on.As shown, however, the arrangement of the lines and the selection in theroup selector will take place as first above escrlbed. An operation,therefore, of the subscribers sending mechanism to send the 100s digit 3will produce seven. breaks in the circuit, hereinbefore described,including the step- ,ping relay 427, the last of such breaks beingrelatively longer than the others of the group. Upon the initialenergization of the stepping relay 427 a circuit was closed by itsarmature over the spring 408 and the back contact of the changeoverrelay 428, including the lower winding of the 100s reg ister 4:29. Thiscauses the energiz'ation of the power magnet of such register and 1tmoybs until whbn midway between its zero or normal position and itsfirst position, its

through #botlrof said windings, or when there is a'. circuit throughneither of said' windings, such regis er will stop; whereas, whena'circuit is closed through but one of said windings the register willmove. The register 429, having therefore been brought to rest betweenits zero and first positions, will await the opening of the circuitthroughi its lowerwindlng at the front contact of the stepping relay 127before moving further. Therefore, as the result of the first impulse orinterruption in the circuit in the operation of the subscribers sendingmechanism, and the consequent deiinergization of the stepping relay 427,the register will move into its first position, the circuit of the upperwinding thererf being closed through the positioning spring 4:71. Uponthe cessation of the first impulse, the relay 427 is again energized,and the register 429 is driven toa position intermediate of its firstand second positions. correspondingly in response to the second impulseit will be driven into its second position. Therefore, as seven impulsesare being received, the seventh impulse will drive the register 429 intoits seventh position. As this impulse isa longer one the stepping relay427 will be deiinergized sutliciently long for its armature to close atits back contact and spring 413 a. circuit for the slow operatingchangeover relay 4% and energize the same. This changeover relay opensthe circuit of the register +29 at its right-hand armature, in order toprevent any false operation of such register, and closes at itsleft-hand armature a circuit over spring 404 for the sequence switch400, driving such sequence switch into its 0th position. The 100sregister has now been set. and it may proceed to control selection inthe group selector. For this pun pose-the outgoing sequence switch 450shown to the right of Fig. 4, and whose springs are all to the right ofthe dotted line, has been started by the closure of :the spring 407bottom as the incoming sequence switch 400 passes through its 5thposition. Before, however. describing the selection controllingoperation initiated by the movement of the outgoing sequence switch 450.further registering operations will be described. Upon the rei'stablishment of the transmitting ciruit. and the consequent energizationof the stepping relay 427, the circuit through the 1,151gss1 controllingposition, the 10s register 4-30 thereby being removed from associationwith the stepping relay, and the units register 431 being placed underthe control of such relay by the closure of the spring 405) bottom. Theclosure of the controlling circuit including the stepping relay 427 andits interruption three times to send the digit 7 will cause the unitsregister 431 to move into its third. position inthe.

manner now well understood, and the final impulse being a long one, thesequence switch 400 will be driven out of its eighth position by theenergization of the changeover relay 4-28. switch 400 will remain untilat the conclusion of the selection controlling operation it is startedin motion to its normal position by a. circuit closed by the outgoingsequence switch $50 in returning tonormal over the spring 407 top. Theregisters have now been set to properly control the/selectioncontrolling operations in accordance with the numerical designation ofthe desired subscribers line; the 100s register has been moved In itsninth position the incoming loo into its' seventh position, the 10sregister" has been moved to its tenth position and the units registermoved into it third position. As the in coming sequence switch 400reached its ninth position a circuit was closed over the spring 42, andthe spring QOlS bottom, to drive the sequence switch 200 out of itsthird into its fourth position, in which position the supervisory relay2:41 again placed under the control ofthe calling subscriber, andthesending circuit from the calling substation is open at thesprings'210 bottom and 211 bottom. The outgoing sequencetswitch' 4 50 ofthe registering and equipment, when it was moved from its first positionas the incoming sequence switch 400 passed through its fifth position asabove described, continued in motion until it reached its fourthposition. In passing determine whether the s digit of the numberregistered was odd or even; it hav ing been foundto be odd, the hundredsregister is in its seventh position, seven impulses having been sent bythe calling subscriber operating his sending mechanism for the digit 3,a circuit \HS closed for the translating relay i312. It will be observedthat the from its first to its second posi- .tion, a test was made bythe spring 41 to spring 474 of the 100s register is closed in thefollowing positions; only a few of which, for clearness, are indicated.upon the clrawings:

The relay was therefore energized, closing by its right-hand armature alocking circuit'for itself including the spring top, and such relay willbe maintained energized until the sequence switch leaves its ninthposit-ion. As the sequence switch 450 passes through its second positionthe closure and subsequent opening of the circuit of the power magnet ofthe 100s register over the spring e58 bottom "will drive such. registerone additional position that is in this case into its eighth position.Also the sequence switch 4-50 passes through its third position thetranslating relay being locked up circuit will he established over thespring 4:60 top, left hand armature of such relay and. spring e61bottom, to drive the 100s register from its eighth'into its ninthposition. 011 coming into its fourth position the sequence switch 600 being already in its third position, the fundamental circuit from theregistering and controlling equipment is closed to the group selectorshown on Fig. 2. Th'is circuit includes the line relay 242 of the groupselector, and the select-ion controlling stepping relay of saidequipment, both of which relays will he energized. This circuit alsoincludes the springs 612, i723, 457 and 611 bottom. The energization ofthe relay 24 2 drives the sequence switclflSOO into its fourthpositi'onover the spring (ll-1;, in which position the circuit for the trippingspindle power magnet 24.3 is closed and the tripping spindle starts inmotion. In moving from position position 1 seitpience switch 600 makesno changes in the fundamental circuit. As the relay 433 was energizedcoincidently with the energization of the line relay 242, it closed thecircuit over the spring 458 top for the loWer winding of the-100%register 429; the register, therefore, nioved a half of a position, thatis, until the closure of the circuit through its npper'winrling and athe positioning spring 4:71 thereof is closed. As the tripping spindleof the group selector began to move it intermittently closecl a circuitto ground, such circuit being so connected to the fundamental circuitthat when it, is closed the relay will be shunted and (le'e'nergizecl,though the line relay 94-2 is maintained energized. This deenergiaationof the relay 433 will take place once for each nioveinent'ot' thetripping spinclle one step I. I" 101 the tripping spine or stage. Uponthe clenergization of the relay the 100's register again moves until itcomes into its tenth. position, iron). which position it will be movedto a position intermediate its tenth and eleventh p0sitions, when therelay is again energized. as the-tripping spindle comes into its set p0-sitionto trip the first set of brushes of th group selector; in thecontinued motion of the tripping spindle a second deiinergization of therelay 33 takes place and the. lOOs register moved into its 11thposition, to he moved again into a. nosition intermediate between itseleventh anti Zero positions, when the shunt is again reinovetl at thetripping spindle. The next closure the earth connection at the trippingspindle, and the consequent third-riei ner ization of the relay drivesthe 100s iter into its zero or normal iiosition. thi osi'tion the U3 isopen and. onseqi t y, not only will the relay 433 remain a" i when theconnection to earth is hro spindle, but also the line r ay EH2- Will becleiinergized, both the to; uinental circ being open. As soon thisoccurs, the circuit.

i open at the front conm i and the trippii Such tripping L three stormor stages, isnow tion to release the third set of brushes on the brushcarriage of the group rtor, as recalled that a trunk line lea-cling tothe group of final selectors in which the desired line appears is to befound in the third bank or level of such group selector.

- As the 100's re ter came into its zero ornorinal position, it the itmining sequence switclwiOO is in its 9th pos tion--that is, it 10s and.units registration is complete--21 circuit wiil he cioseii including thesprings 56, -772 and 4-10 to drive me ting sequence switch 45-? into itsGt i which it is ready to control te soon. as an idle trunk line aproper final selector has been tamsl and. seiseil in the group selector,will be described. It the incoming sequence switc 3, 4:00 is notes yetin its 9th position, the outgoing sequence switch 450 will remain its.tth position, moving into itsfith pUSlhlC'l'l as soon as the sequenceswitch 400 reaches its 9th position.

When the line relay i249. stopped the move ment' of the tripping;spindle of the group selector, it also ch std a circuit over its backcontact 21316 tis spring 602 to back contact and armature of the relay','Wl1ici1 is deenergized after the sequence switch 600 left its 3rdposition, {uni spring 607 bottom, to drive the sequence switch 600 intoits -5th position. In the 5th position a circuit will he established forthe group selector power magnet M4, including the spring 603 hothen atthe tripping v tom, the back Contact and armature of relay 237, sequenceswitch spring 602 top. and the back contact and armature of the linerelay 24:2. The brush carriage of the group selector, therefore, willbegin to move in its movement. causin the proper set of brushes to bereleased in the movement past the said tripping spindle and then causingsuch. re" leased brushes-2&5, 246 and 247 to make-coutact with thevarious sets of contacts in the selected level. So long as the testbrush makes contact With the test terminals of trunk lines which arealready engaged, insuiiicient potential Will'be found thereon toenergize the relay due to the fact that the low resistance Winding of arelay correspondingto the relay 2 35 of some other group selector isalreadv connected to the terminal multiplied to such test terminal. Assoon, however. as the brushes come in contact with a set of terminalsindividual to an idle trunk line, full potential will be found on thetest tern'iiual thereof. and a circuit will be established for the testrelay 235 extending from battery at final selector over the spring 312bottom, spring 314 top, the left winding of the relay 331, testconductor of the seized trunk line. test brush 24'. of the groupselector, right-hand high resistance winding; of the test relay 235,spring; 605 top, power control test relay and spring 606 top to ground.The test relay 2.? will be energized but the relay 237 will not beenergized owing to the shunt therearound existing over the interrupterbrush lhe energization of the relay closes a low resistance circuitthrough its left-hand Winding parallel to its rightdiand winding, whichso reduces the potential upon the test terminal of the trunk line thatthe test relay of no other group selector, the brushes of which come incontact with the terminals of such line, will be energized. As soon asthe brush carriage, which is continued in motion, properly centers thebrushes upon the terminals of the seized line, the shunt circuit throughthe interrupter brush Will be open and the relay 237 will be energized.The energization of this relay will open the circuit for the powermagnet- 244 and close the circuitfor the holding magnet 250 over thesprings 608 top and 607 top, so that the brush carriage of the groupselector will "be properly and accurately stopped in thewell-knownmanner. The energization of the relay 237 has also closed Ia'circuit for the sequence switch 600 to drive such sequence switch intoits 6th position. In this position of the sequence switch 600 thefundamental circuit is connected through from the final selector to theregistering and controlling equipment, and the closure of this circuitat this time depends upon Whether the outgoing sequence switch 450 hasreached its 6th position. When the sequence switch 450 was driven out ofits fourth. position upon the completion of the hundreds selectioncontrolling; operation it moved directly into its sixth position but inpassing through its fifth position the moinentary closure of the spring462 bottom has driven the tens register into its eleventh position inthe now wellauiderstood manner. When new the funilaniental circuit isagain closed in the sixth position of the sequence 'magnet 333 is closedover the spring; 809.

bottom and the front contact of the relay 332. The tripping spindle willthereupon begin to move. The energization at this time of the relay 433has closed a circuit over the spring; an top to move the tens registeronehalf of a. position from the position in which it was set asdescribed.

it will be recalled that the 105 digit of the desired line zero and,therefore. such line is to be found in the first bank or level of thefinal selector. It will therefore be necessary that'the selectioncontrolling operation of the final selector should be tor-- initiatedwhen the tripping: spindle has moved one step or stage and is inposition to release the set of brushes corresponding to the first bankset or level oi contacts. it will also be recalled that the tensregister Wasset by the subscriber in its 10th position and subsequentlymoved to its eleventh position. lVhen. therefore, the tripping spindleat the final selector moves its first stepfjor stage. the shunting ofthe relay 433 in the Well-known manner drives the tens register. intoits zero on noi'inalposition. This movethe fundamental circuit at thespring 483 of such register, so that when the shunt circuit through thetripping spindle is opened both the relay 433 and the relay aredeenergized. At the same tiinethe closing of the spring 482 of the tensregister closed a cir cuit including the springs 411. 482 and 463' topto drive theyout-going sequence switch 450 into its 8th position-readyto control .ment of the tens register immediately opensdeenergization of the line relay 332 as just described the movement ofthe tripping seventh position upon the termination of tens selection themomentary closure of the spring it). moves the units register one midi--tional position so that w zen the sequence switch stops in its eighthposition and again closes the fundamental circuit the units register isin its fourth'position. The closure at this time of the fundamentalcircuit again energizes the relays and 433, but this time in the 4thposition of the sequence switch 300 end the 8th position of the sequenceswitch 450. In the sith position of the sequence switch 300 theenergizetion of the relay 332 closes at circuit over the scoring 306 topfrom the brush carriage power magnet of the final selector, and suchbrush can riage begins to move. In the initial move ment of the brushcarriage, the proper set of brushes (in this case the first set} istripped as the carriage passes the tripping spindle. In the subsequentmovement of the brush carriage the brushes 334;, 336 sweep over the setsof terminals individual to the lines niultipled to this hunk or level ofcontacts. For each movement of such brushes to a set of terminals theinterrupter device 337 closes a circuit to ground from the fundamentalcircuit over the springs 313 top and 315 in the well-lmown manner, suchcircuit to ground as is well understood shunting the relay whilemaintaining the relay 332 energized. Upon the energization of the relayand its subsequent intermittent denergzizotion due to the shunt inc;action of the contacts of the interrupter 337 at the final selector, theunits register will he stepped in the well understood man nor, one fullposition for each energizetion and subsequent deiinergizetion of therelay 433. At the end of eight of such operations of the relay the unitsregister will enjoin be in its normal position, the selected brushes ofthe final selector at this time being; shout to make contact with the8th or No. 7 set contacts of the bank or level to which they areindividual. It will be recalled, however, that since the desired linelocuteo in an. odd hundred, the particular line desired is to be foundin the second half of the fi cl selector, and it is therefore if .rythat the selecting operation should not terminate at this time; Forthieirezison the fundamental circuit is not opened at this time at thespring 4923 as would be otherwise the case,-

a shunt being maintained about such spring, such shunt including;- thespringi-(SO bottom, let" hand armature of the trunsiuting relay i 11 owlthe spring l'iil' top.

It 'will be recalled that the relay 432 was locked up when the sequenceswitch 450, in passing from its first to its second position, tested thecondition of the 100s register e29, and on finding it in a positioncorresponding to an odd hundred, completed the circuit for thetranslating relay The fundamental circuit not being open at this time,the brush carriage at the final selector will continue to moveuntil theunits 1e ister -l3l has made a complete revolution as a result of suchmovement. register will take twelve additional steps. It will now beseen for what purpose the two additional notches in the interrupterplate of the final selector are provided, as hereinbefore described. Toreach the contacts of the desired line after the units register hasfirst reached its normal position would otherwise produce only tendenerg'izations of the stepping relay 433, and,

This means that the unitsconsequently, only ten steps by the unitsregister. Since it is necessary that the llllltS register should comeinto its zero or normal position in order to cause the cessation ofselection, it is necessary that two additional steps be provided forand, consequently, two additional notches are cut in the interrupterplate of the final selector to produce such steps. Therefore, after thestepping relay 4.33 has been operated twelve 'additional times, and usthe selected brushes of the final selector ere coming into contact withthe 'ith set of terminals in. the second half or range of the selectedbank or level of the final selector, the units register will again be inits normal position. As the units register passed its normal positionWithout stopping, as above described, circuit was closed by r'he spring492 over the spring 463 bottom to drive the sequence switch 450 out ofits 8th endinto its 10th position, this circuit being only maintainedmomentarily by the spring 49 The sequence switch stopped in its 10thposition. When now the units register i231 comes a. second time intospring 493 thereof being opened at the springs M50 bottom and 461 top,the fundamental circuit is immediately opened, producing thedeenergizatiomiu the'manner Well understood. of the relays 332 and 433to terminate selection in the final selector. The un s register 431coming into its normal position again closes the spring 4 92, and thesequence switch 450 returns to its nor-. mail position, in whichmovement in passing through position 11 it closes a circuit at springbottom to return the sequence switch 400 to its normal position. Itshould be also noted that the sequence switch 450, on leaving its 9thposition, opened the looking circuit of the translating relay 432. Thedesired line now having been selected, the services of the registeringand controlling spring 314 top.

equipment are no longer required for this connection, and, therefore, asthe sequence switch 400 left its 9th position the spring 406 opened thecircuit for the relays 1126 and 240, which circuit had been substitutedfor the one originally established over the spring r05 as the sequenceswitch 400 left its first position. The relays 426 and 240 are thereforedeenergized. The ene. ization of the relay 426, and the restoration ofthe sequence switch 400 to normal will :ause the registering andcontrolling equipment shown on Fig. 4 to test. idle and agiiessible toany connecting circuit taken for use which has access to' it. At thesame time that the relay 426 is deiinergized the relay 24:0 wasde'nergized and by the retraction of its armatureclosed a circuit todrive the sequence switch 600 from its sixth'into its seventh position.

In this movement, however, the contact 611 top is closed and thesequence switch 200 is 'driven from its fourth into its fifth positionfIn these positions the sequence switches-(300 and 200 await the furtheroperations of the final selector apparatus shown on Fig. 3.

energized, and cltmed for itself a circuit to take the place of thecircuit through the spring 312 bottom, which is opened as the sequenceswitch 300 leaves its first position. As the sequence switch moves fromits fourth to its fifth position, the-spring 314 .top is opened and 314bottom is closed. The

relay 331 is maintained energized. both of its windings nowbeingincluded in the circuit and the battery is connected over the spring 314bottom to the power control test relay 339. At the same time the spring307 top is closed, connecting battery with a "high resistance winding ofthe test relay 349. The fifth position of the sequence switch 300 is thetesting position thereof. If in this positipn full potential is foundupon the test terminal 342 of the desired line, indicating that the lineis idle, the test relay 3%!) will be energized-over its right hand highresistance winding. If on the other hand the normal potential 'upon suchtest terminal is reduced by such line being busy. either as a callingline or a called line. as will occur in the well-known manner. the testrelay 349 will not be energized. Assuming first that the line is idleand that such relay is conscqucntly energized. it closes over itsarmature a circuit, through its low resistance left This is the throughor talking position of this sequence sw1tch.

This relay was therefore.

into its eighth position.

- hand winding and the test relay 339, in parallel to its right handwinding, which will so reduce the potential of the test terminal of suchseized line that it will test busy in all other final selectors in whichit appears. Such circuit will also energize the relay 339 and when thesequence switch 2300, comes into the sixth position, it will findcircuits closed, one over the spring 317 and the other over the spring305 bottom, and the front contact of relay 339 and the back contact ofrelay 332, to move it into its tenth position, in which position, andalso in the eleventh position a circuit will be found closed to move itinto its twelfth position. The sixth position of this sequence switch isprovided for hunting an idle line to aprivate branch exchange, in casethe particular line selected is found busy. The apparatus for performingthis operation is not shown, however, and in order to drive the sequenceswitch through its siXth position, which is, as" shown, an idleposition, whether the desired line is found idle or busy, the spring 317is provided. 'The twelfth position of the sequence switch 300 is theringing position. in this position ringing current is projected over thecalled line by the closure of the springs 310 bottom and31-1 bottom. Asthe sequence switch 300 passed through its eighth position, the trunkline leading to its final selector was shortcircuited by the closure ofthe spring 309 bottom. This causes the momentary energization of thesupervisory relay 248, which by the attraction of its armature drivesthe sequence switch200 This would cause the subscriber to receive thebusy tone by the closure of the springs 212 bottom and 213 top. exceptfor the fact that almost immediately after as the sequence switch 300passes from its eleventh into its twelfth position, the spring 30!)bottom is again closed energizing the relay 248 to drive the sequenceswitch 200 into its eleventh position. in this position of the sequenceswitch 200, the springs 212 top and 213 bottom being closed. thesubscriber receives the distinctive ringing tone, and will continue'tore-' ceive such tone so long as the sequence switch 300 remains in itstwelfth position. long as the called subscriber does not respond,insufficient current will pass over the ringing relay 343 to energizeit'. As soon. however, as the path for direct current is closed at thesubscrihers substation, bythe removal of his receiver fromits switchhook, the relay 343 will be energized and drive the sequence switch 300into its thirteenth position. In this position the circuit is closedthrough from the battery and repeating coil shown in Fig. 2 to thecalled subs'cribefs substation, and the relay 248 is thereforeenergized. driving the sequence switch 200 out of its eleventh and intoits fourteenth position. The sequeiice switch 100 being in its fifthposition,'the sequence switch 200 being in its fourteenth position, thesequence switch 600 being in its seventh'position, and

the sequence switch 300 being in its thir 'teenth position,the callingsubscriber and, the called subscriber are now connected, each subscriberbeing supplied with transmitter current from the battery; shown inconnection with the repeating coil Conversation may now take place. v

- Disconnection ellpon the termination of conversation, one or bothsubscribers return their receivers their respective switch 15 hooks,thereby opening a circuit over which the supervisoryrelays 241 and'248.are maintained energized. Assuming that the called subscriber firstrestored his receiver to' its switch hook, the deenergization of therelay 248 closes a circuit over the spring 203 and 209 bottom, todrivethe sequence switch 600' out of its seventh position and intoitseighteenth position. In this movement the sequence switch 600 closed inits 8th position a circuit over thesprings 609 and 202 top, to drive thesequence switch QOO baCkfO its normal position. On coming into its 18thposition the sequence switch 1600 established the usual restoringcircuit for the brush carriage of the group selector, and such brushcarriage moves until the brush 244 of the interrupter comes in contactwith the normal segment, at which time circuit is closed. over thespring 618 to energize the relay 237 which'stops the movement of thebrush carriage in the usual manner and drives thesethis relay'is againestablished, provided the calling subscriber has not restored hisreceiver to its switch hook, which includes the spring 108 bottom, thespring 111, the-substation circuit and the spring 112 top; The sequenceswitch 100 wiil'therefore stop in its 9th position and remain thereuntil the subscriber opens the circuit to direct current at hissubstation by replacing his receiver upon its switch hook. As soon asthis occurs, the relay 137 will again be denergized and drive thesequence switch 100 be oh: to its first or normal position. It will beobserved that the cut-0H; relay 139 is controlled through the 7thposition by a circuit including the spring 102 top. and in the 8th or9th position by acircuit including the resistance 199 and the spring110. This transfer of control. is accomplished before the circuit of thecutoff relay 139 was opened at the spring 207. As the sequence switch600 left its 7th posise ector. This relay therefore immediately tjion,it opened at the springs 605 top and to the circuit for the relay 331 atthe finalallowed its armatures 'to ,retract, its left hand armatureclosing a circuit 'over the spring 308 bottom to energize the line relayThe energization of this relay drives tion into its 16th position.- Oncoming into 'itsi 16th position, the circuit at the called subscriberssubstation being already opened, the relay 332 is Without current andtherefore is denergized, driving the sequence switch 300 into its-18thposition. In this posit-ion of the sequence switch 300 the usualcircuits are established to restore the switch carriage of the finalselector. to normal.

lay 331 controls through its right-hand armature the energizing currentfor itseliin the sequence switch 300 out of its'13th posi'- 4 allpositions, except position 1, of the sef quence switch 300. However, inositions 8 to 17 a testguard is maintaine terminal of the trunk line bythe closure of the spring 610 bottom. Assuming-.thatthe callingsubscriber first restored h s receiver to its switch hook, th'erestoration tb normal of the group selector apparatus, the sequenceswitch. 600," sequence switch 200 and the line finder apparatus, willvtake place precisely as has been hereinbefore described, ex ceptthat'these operations are initiated by the denergization of thesupervisory relay 241 instead of by the deenergization of thesupervisory relay248, as has been described,

with the further exception that the sequence 1 switch will not stop inits 9th position as the circuit for the relay 137 over the callingsubscribers line willznot be established. At the filial selector,however, when the se-- quence switch 300 comes into its 15th and 16thpositions the called subscriber not as yet having restored his receivertoi ts switch hook, a circuit will be established for the relay 332,including the springs 308 top, 310.

top, subscribers line, 311 top and 309 top.,

on the lot Therefore, when the sequence. switch 300 mes into its 16thposition it will'there stop and await the restoration of the calledsubscribers receiver-to its switch hook, which, when it occurs, willopen the circuit to the relay 332, all-owing such-relay to-deenergize,

to drive the sequenceswitch 300 .out of its 16th position, after whichthe restoration of.

' throu 11 its Sthposition', it will bc iecalled that t e closure of thespring 369 bottom the final selector apparatus will take place as hasbeen hereinbefore described. v

Attempted connection to a busy Zine-If after the final selector switchhas been moved to bring its brushes 33 i, 335, 336 intov contact withthe terminals of the desirerlline, and the sequence switch 300 is-moving through its5th and 6th positions, such line should be foundbusy, insufiicient potential will exist upon the test terminal 342 toaccomplish the energizationof the relay 34:9, consequently, noenergization of the relay 339 will take place and when the sequenceswitch 300 comes into its lOth position it will stop, and therestoration of the brush carriage of the selector 'Will take place overa circuit including the armatureand back contact of the relay 332,armature and back. contact of the relay 339, and spring 306 bottom. Asthe sequence switch 300 passed caused the energization of thesupervisory relay 248130 drive the sequence switch 200 into its 8thposition. In this position the busy tone is applied to the trunk lineand the calling subscriber is thus notified of the busy condition of thedesired line. When its the brush carriage of the finalselector reachesits normal position the relay 332 will be energized by circuit includingthe normal segment of the interrupter 337, and the sequence switch 300will be driven into its 11th position. The circuit for such relay 332being opened at the spring 313 as the sequence switch leaves its 10thposition, .the sequence switch 300 will stop in its 11th position. Thissequence switch will remain .in this position and the sequence switches600 and 200 will remain in their 7th and scribers line being entirelyunaffected) until the calling subscriber restores his receiver to itsswitch hook when in response to the'de energization of thesiipervisoryrelay 241 the sequence switch 200 will'be driven from its 8th into its11th position. As it comes into its 9th position circuit will beestablished over the back contact of the supervisory relay.'and' thespring 209 bottom, to drive the sequence switch (300 out of its 7thposition, from which position the restoration of the group selectorswitch. the sequence switch (300, the sequence switch 200 and theapparatus of the first finder will take place precisely as has beenhcreinbctore described.

.I m'thermore. the restoration of the final selector apparatus will alsotake'place as hereinbetore described iimnediately that the relav 331 isdei nergizcd as the sequence switch (300 leaves its 7th position.

'lrmnufiurc dlrhLU'll'II(5(7i7:())'1..?If the calling subscriber shouldrestore his receiver to its switch hook in the third position of thesequence switch 200, the dci nergization of the stepping relay willcause the energization of the change-over relay F28, and the 'relay427.1'emaining deenergized and the relay 428 energized, the incomingsequence switch 400 will be driven directly into its ninth position,from whatever position it maybe at the time. When sequence switch lOOreaches .its ninth position, the sequence switch 200 will be driven fromits third into its fourth position as has been hereinbet'ore described.

The sequence switch 200 will then be further driveninto its eleventhposition by the closure of a circuit over the back contact of thesupervisory relay 241,- and from such the receiver to its switch hook atany time after the sequence switch 200 has left its third position andbefore it comes into its eighth position, the de'nergization of thesupervisory relay 241 will drive the sequence switch 200 into itseleventh position from which the restoration of all the apparatus willtake place as hereinbefore described, On any occasion of prematuredisconnection which takes-place when the registering controllingapparatus is in an off-normal condition, the deenergization of thestarting relay 426 will insure the restoration to normal of the variousregisters of the registering and controlling equipment. Thedeenergization fora prolonged period of the stepping relay 427 causesthe change over relay 428 to beenergized sufficiently long to drive thesequence switch 400 into its ninth position, In passing through itsfifthposition, the sequence switch 450 is started in motion as hereinbeforedescribed. 011 coming into its fourth position. it it is not already inthis position, the-starting relay 426 being now dei nergized, a circuitis established for the stepping relay 433 which includes the backcontact and left hand armature oi the starting relay, spring 473 ofthe'humlreds registcnspring 457 and back contact and right armature ofthe-starting relay +26. The stepping relay "433' being energized acircuit is closed'through the lower winding oi the power'niagnet oi thehundreds register and the register will start in motion. It will beobserved that the circuit through the spring 471 and the upper windingof the power magnet m the hundreds register is

